Copper Tape!
:-P Inside joke, Copper Tape seems to be the duct tape of my place.
On 9/28/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > to reduce the peaks even more you may double up your tants if that
> > is possible with your parts/layout.
>
> Not really. I can double up ceramics because
> Put them sideways. Then you can put two Tants. in the one
> footprint. Assuming there is enough metal at the edge of the
> "bottom", there has been in the past.
There isn't. The metal is narrower than the cap.
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On Thursday 27 September 2007 08:09:34 pm DJ Delorie wrote:
> > to reduce the peaks even more you may double up your tants if that
> > is possible with your parts/layout.
>
> Not really. I can double up ceramics because the metal goes all the
> way around, but for the tants the metal is only on th
> to reduce the peaks even more you may double up your tants if that
> is possible with your parts/layout.
Not really. I can double up ceramics because the metal goes all the
way around, but for the tants the metal is only on the bottom. Plus,
I'm already putting 1206 caps on 0805 footprints.
to reduce the peaks even more you mau double up your tants if that is
possable with your parts/layout.
:-)
Sorry i never got to doing the math with your curents and voltages
work crept up on me and sent me to china.. Hellos to all from
Shanghai.
On 9/28/07, DJ Delorie <[EMAIL PROTECTE
I got the new parts today.
Redux:
Adding 100uF electrolytic, swapping in 10u 25v 1206 ceramic did NOT
get rid of the buzzing, just reduced it a little.
Swapping in 10u 16v 1206 tantalum with the 100u DID get rid of the
buzzing, both the low pitch and high.
There's still 80mV P-P spikes on the
> can you capture a current trace, knowing that information will
> provide us an ability to actually calculate the required capacitance.
10 ohm resistor between the LDO and the control transistor (LDO ->
resistor -> P-MOS -> cap -> OLED).
~300mV Vpp ripple across the resistor, 30mV to 300mV a
> What about switching to tantalums? I can fit the EIA 3216
> (1206-sized) parts in that slot, allowing a 10uF 16v tant instead of
> the 22uf 16v (or 10uF 25v) ceramic.
Using a tantalum should solve the problem. From the same article, "Use
a different type of capacitor, such as tantalum"
__
can you capture a current trace, knowing that information will
provide us an ability to actually calculate the required capacitance.
Where i work we do not use tantalum caps because there down sides are
pretty big in terms of safety.
when you over work a tant, they get very hot.
It shoul
On Sep 19, 2007, at 3:08 PM, DJ Delorie wrote:
>
>> Kemet does have a "surge-robust" family, the T495 series.
>> http://search.digikey.com/scripts/DkSearch/dksus.dll?
>> lang=en&site=US&keywords=Kemet+Tantalum+T495&x=0&y=0
>
> Grr, nothing small enough.
>
> OTOH, would the LDO limit the inrush c
> It should. The other thing to check is ripple: if you're getting
> enough to make a ceramic sing, the ripple current might be a problem
> for Ta. Check the ripple voltage and frequency across the cap and
> use the resistance and capacitance ratings to deduce a current.
Yeah, the ripple voltage
> Kemet does have a "surge-robust" family, the T495 series.
> http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&keywords=Kemet+Tantalum+T495&x=0&y=0
Grr, nothing small enough.
OTOH, would the LDO limit the inrush current?
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On Sep 19, 2007, at 1:34 PM, DJ Delorie wrote:
>
>> Tantalums will work. Just make sure you get "surge rated" parts.
>
> Hmmm... how would I know? That's not one of the checkboxes on the
> digikey search engine.
Sometimes catalog searches don't tell all.
Kemet does have a "surge-robust" family
On Sep 19, 2007, at 1:12 PM, DJ Delorie wrote:
>
>> Most relevant part of that article, "Use a part with thicker
>> dielectric, usually corresponding to a higher voltage rating. This
>> reduces the voltage gradient, which reduces piezoelectric noise, if
>> the package size increase is acceptable."
> Tantalums will work. Just make sure you get "surge rated" parts.
Hmmm... how would I know? That's not one of the checkboxes on the
digikey search engine.
> Otherwise, watch out for explosions at power-up.
Or, in this case, activating the OLED. Its power is controlled by the
CPU.
_
Andy Peters wrote:
> Tantalums will work. Just make sure you get "surge rated" parts.
> Otherwise, watch out for explosions at power-up.
3 ohms/volt dropper (5v = 15R dropper) to limit the surge was the standard
I learnt and still use. Suitably adjusted/amended to allow for the load
current.
> Most relevant part of that article, "Use a part with thicker
> dielectric, usually corresponding to a higher voltage rating. This
> reduces the voltage gradient, which reduces piezoelectric noise, if
> the package size increase is acceptable."
What about switching to tantalums? I can fit the E
> (Possibly) Interesting article about the piezo-electric effect in
> ceramic capacitors:
Most relevant part of that article, "Use a part with thicker
dielectric, usually corresponding to a higher voltage rating. This
reduces the voltage gradient, which reduces piezoelectric noise, if
the package
On Sep 19, 2007, at 11:42 AM, DJ Delorie wrote:
>
>> What dielectric are those ceramic caps? Y5V, X5R, X7R?
>
> X5R
>
(Possibly) Interesting article about the piezo-electric effect in
ceramic capacitors:
http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/
242F5F2E69DCEC7485256EDF
On 9/19/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
> Besides, as I've said before, the ringing's waveform corresponds to
> the data on the OLED, like a video signal. It's not a constant ripple
> like a power supply problem, and goes away when the oled is filled
> with all dark pixels.
Have you lo
> What dielectric are those ceramic caps? Y5V, X5R, X7R?
X5R
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> The caps are 4.7uF 16v. They're decoupling/bypass for a +12v rail
> (well, one is, the other is VcomH, which seems to be 7v). They're the
> biggest 0805's with that voltage rating.
What dielectric are those ceramic caps? Y5V, X5R, X7R?
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> Or is it reacting too quickly? Some power supplies need a minimum ESR
> so that the output cap acts as an RC filter.
The LDO has its own bypass cap (0.1u) at its terminals. The 4.7u is
after the transistor that enables the rail to the OLED. It buzzes
with both PNP and P-MOS, and those should
DJ Delorie wrote:
> The caps are 4.7uF 16v. They're decoupling/bypass for a +12v rail
> (well, one is, the other is VcomH, which seems to be 7v). They're the
> biggest 0805's with that voltage rating.
>
> I can fit a 1206 in that spot. If I replace those with 10uF 25v, do
> you think they'll n
On Wed, Sep 19, 2007 at 01:30:33PM -0400, DJ Delorie wrote:
>
> > The PCB for my alarm clock buzzes.
>
> If I replace just the +12v cap with a 22u elec, the +7 cap still
> buzzes. I suspect the elec alone can't react fast enough to get rid
> of the ripple.
Or is it reacting too quickly? Some p
> The PCB for my alarm clock buzzes.
Having poked and prodded, and getting a piezo unit that did nothing, I
finally figured it out (the trick was to use a nail, not a toothpick,
to poke and prod - I was using that as a better sound conductor for
the piezo).
There are not one but TWO buzzing caps
On Sep 15, 2007, at 1:17 AM, Steve Meier wrote:
>>> You are just jealous that I come up with such elegent solutions
>>> (mine
>>> have even avoided caustic fluids liberaly mixed with copper). Yes I
>>> have
>>> a right to be smug since, I know others where thinking a shotgun
>>> approach.
>>
>>
Dave McGuire wrote:
> On Sep 14, 2007, at 11:55 PM, Steve Meier wrote:
>
>> You are just jealous that I come up with such elegent solutions (mine
>> have even avoided caustic fluids liberaly mixed with copper). Yes I
>> have
>> a right to be smug since, I know others where thinking a shotgun
On Sep 14, 2007, at 11:55 PM, Steve Meier wrote:
> You are just jealous that I come up with such elegent solutions (mine
> have even avoided caustic fluids liberaly mixed with copper). Yes I
> have
> a right to be smug since, I know others where thinking a shotgun
> approach.
Well I suppose
Dave,
You are just jealous that I come up with such elegent solutions (mine
have even avoided caustic fluids liberaly mixed with copper). Yes I have
a right to be smug since, I know others where thinking a shotgun approach.
By the way you might want to put a plastic bag over your display before
y
On Sep 14, 2007, at 9:43 PM, Steve Meier wrote:
> I suggest stopping trying to solve this problem using itellect. At
> times
> shots in the dark workbest. Take your board outside at night and take
> your 22 with you set the board up in a safe spot and there in the dark
> aim for where the buzzing
On Friday 14 September 2007 09:00:33 pm DJ Delorie wrote:
> > Do you really want all of that eletricmagnetic "junk" by your head?
>
> The clock I'm replacing has a plain old motor in it. Isn't that
> giving out far more EM junk than some microelectronics?
There is a belief that modulated fields a
I suggest stopping trying to solve this problem using itellect. At times
shots in the dark workbest. Take your board outside at night and take
your 22 with you set the board up in a safe spot and there in the dark
aim for where the buzzing sound is comming from and fire. Repeat the
last step until
DJ Delorie wrote:
>> Rather than trying to find out what is buzzing, can you find out
>> what is not buzzing, or make the problem worse to make it esier to
>> find?
>
> So far, I haven't been able to affect the sound in any useful way,
> just a few useless ways.
The buzzing's audible, you said.
> Do you really want all of that eletricmagnetic "junk" by your head?
The clock I'm replacing has a plain old motor in it. Isn't that
giving out far more EM junk than some microelectronics?
> Rather than trying to find out what is buzzing, can you find out
> what is not buzzing, or make the pro
On Thursday 13 September 2007 06:56:44 pm DJ Delorie wrote:
> My wife said the same thing. However, *this* board is going in my
> bedroom, on a table near my pillow, while I'm asleep.
Do you really want all of that eletricmagnetic "junk" by your head?
Louis Slesin of Microwave News states:
mic pre-amps are more sensitive than you scope's input stage. perhaps
not as accurate, but there made for low level signals.
unless you are putting your microphone through a pre amp into your
scope, you won't see such a quiet signal.
i have done this with an iMic (http://www.griffintechnolo
> Take a FFT of the sound.
My scope has FFT built in. I just can't get a microphone to pick it up.
> you could be hearing a beat frequency of 19th or 20th harmonic of the
> 7.8 kHz oled, and the 150kHz switcher
Except it happens when the switcher is off, too.
__
Take a FFT of the sound.
use this software or another like it.
http://www.arachnoid.com/FFTExplorer/index.html
use a good sound card if you can afford it.
you could be hearing a beat frequency of 19th or 20th harmonic of the
7.8 kHz oled, and the 150kHz switcher
7.8 * 19 = 148.2kHz :-)
> DJ, your LCD has a back light, doesn't it?
It's not an LCD. I chose OLEDs specifically because they didn't need
a backlight.
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> ... and the buzz was worst when it was right on top
> of the MRC's LCD. Very weird.
I've been following this sort of off and on, so forgive me if this has
already been mentioned.
DJ, your LCD has a back light, doesn't it? I've seen touch-sensitive
screens using flourescent back lights which a
On Sep 12, 2007, at 9:34 PM, DJ Delorie wrote:
> The PCB for my alarm clock buzzes.
>
>
> 2. What kind of components *can* make that kind of noise?
>
> 3. If you know what's causing it, how do I fix it?
Once upon a time I was at the local rock venue doing a soundcheck and
one of the musicians o
> No oled no noise? with oled noise but comming from the board. Could
> it be the connector?
I've poked the connector to no avail.
I don't have a piezo element at the moment, else I might have better
luck tracking down the actual source of the noise.
___
No oled no noise? with oled noise but comming from the board. Could it
be the connector?
On Fri, 2007-09-14 at 14:53 -0400, DJ Delorie wrote:
> > The OLED has noise on it 0.5V. What frequency?
>
> Line redraw noise is about 7.8khz, with the waveform dependent on
> what's on the screen. That's t
> The OLED has noise on it 0.5V. What frequency?
Line redraw noise is about 7.8khz, with the waveform dependent on
what's on the screen. That's the high pitched whine portion.
5.5ms of that noise, followed by 1.5ms of quiet, about 140Hz vertical
refresh. That's the buzzing portion.
> The swi
Going way back in this conversation.
The OLED has noise on it 0.5V. What frequency?
The switchers are opporating at 150KHz.
What frequency is the buzzing?
Could the two noise signals be mixing?
Could a capacitor be humming like a tunning fork with respect to one or
more of the noise signals?
> > How good is the temp. control on your oven?
>
> Er, zero control. I use a hotplate, which heats only the back of the
> board, so the solder melts before the chips get too hot. However,
> it's a $20 item, and basically has "on" and "off" settings.
>
> What I do is turn it on and wait. About 3
> How good is the temp. control on your oven?
Er, zero control. I use a hotplate, which heats only the back of the
board, so the solder melts before the chips get too hot. However,
it's a $20 item, and basically has "on" and "off" settings.
What I do is turn it on and wait. About 3 minutes la
> Ok, here's a random thought. What if the hotplate reflow delaminated
> one of the layers? You'd still need a cause, but it would make the
> cause's minimum size smaller.
>
> Of course, there's no *visible* effect on the pcb from the hotplate,
> not even a mild yellowing on the back.
How good i
Ok, here's a random thought. What if the hotplate reflow delaminated
one of the layers? You'd still need a cause, but it would make the
cause's minimum size smaller.
Of course, there's no *visible* effect on the pcb from the hotplate,
not even a mild yellowing on the back.
___
> 1) Have you put a "reasonable" 16 ohm load across the speaker pins of
> U302 and U303?
Done, no change.
> 2) The datasheet for TDA7056 shows a 5K resister between the input pin
> and ground.
It shows a 5k input impedance in the test circuit. The other circuit
doesn't have the resistor. My r
1) Have you put a "reasonable" 16 ohm load across the speaker pins of
U302 and U303?
2) The datasheet for TDA7056 shows a 5K resister between the input pin
and ground.
3) from the dac to the speaker drivers you have an R C could you be
getting a parallel inductance back through ground? Try shorti
> can I see a bom or schematic?
http://www.delorie.com/electronics/alarmclock/20070913-design.zip
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can I see a bom or schematic?
On Thu, 2007-09-13 at 22:27 -0400, DJ Delorie wrote:
> > also re-read the data sheets any chance you tied a reference output
> > to ground?
>
> Which chips would have these? The OLED has a few pins that "must
> remain floating" and they're floating.
>
>
>
> also re-read the data sheets any chance you tied a reference output
> to ground?
Which chips would have these? The OLED has a few pins that "must
remain floating" and they're floating.
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also re-read the data sheets any chance you tied a reference output to
ground?
On Thu, 2007-09-13 at 22:18 -0400, DJ Delorie wrote:
> > Or, try lifting the power pins one component at a time. And if it buzzes
> > it must be oscillating and should be viewable with your oscope.
>
> Just tug on the
unsolder them and slide an insulator between the pin and the pad.
On Thu, 2007-09-13 at 22:18 -0400, DJ Delorie wrote:
> > Or, try lifting the power pins one component at a time. And if it buzzes
> > it must be oscillating and should be viewable with your oscope.
>
> Just tug on them, or unsolde
> Or, try lifting the power pins one component at a time. And if it buzzes
> it must be oscillating and should be viewable with your oscope.
Just tug on them, or unsolder them?
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Or, try lifting the power pins one component at a time. And if it buzzes
it must be oscillating and should be viewable with your oscope.
Steve M.
On Thu, 2007-09-13 at 20:42 -0400, Randall Nortman wrote:
> On Thu, Sep 13, 2007 at 08:35:35PM -0400, evan foss wrote:
> > I have had audio amplifier
> P.S. Aren't you glad the minimum board buy at the PCB vendor was
> three? ;-)
It wasn't. It was one. I have customers for the other two.
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On 9/13/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
> At this point, no suggestion is silly enough to insult me.
* You could try freeze spray on individual components.
If building up another board testing section by section doesn't
help find the fault in your first board you could try operational
> The ethernet uses a galvanic isolation power supply? One of those
> XXv to 9v DC converters? Tried to eliminate that? It hasn't anything
> to do with the oled circuitry though...
It's an ENC28J60 with a pulsejack (internal magnetics).
I.e. one chip, one RJ45, and a handful of 0603 discretes.
On Thu, 13 Sep 2007 17:23:56 -0400
DJ Delorie <[EMAIL PROTECTED]> wrote:
> The only thing on the bottom of the board is a couple of bypass caps
> (most are on the top) and some of the ethernet bias circuitry.
The ethernet uses a galvanic isolation power supply? One of those XXv to
9v DC converter
> One good way to address this and other such possibilities would be
> to start de-soldering each component that is not strictly necessary
> to drive the OLED.
It doesn't bother me THAT much ;-)
> If you get down to just the CPU, OLED, and required support
> components, I would go so far as to r
On Thu, Sep 13, 2007 at 08:35:35PM -0400, evan foss wrote:
> I have had audio amplifiers and large transistors in general buzz on
> their own. Are you sure it is really on standby?
One good way to address this and other such possibilities would be to
start de-soldering each component that is not s
> I have had audio amplifiers and large transistors in general buzz on
> their own. Are you sure it is really on standby?
Yes, I checked the control pin.
I just tested it with the amps on, too. No change.
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I have had audio amplifiers and large transistors in general buzz on
their own. Are you sure it is really on standby?
--
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http://evanfoss.googlepages.com/
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> Have you made sure that both ends of all the components are solidly
> attached? It'd be easier to miss something like that with a reflow
> build than if you'd personally touched each component with an iron.
At this point, all the components on the +12v net have been manually
soldered. Mostly
> Not to be insulting but is the speaker connected?
Heh. No, the speakers are not connected. Yes, they do buzz if you
leave the audio amps running. No, I don't leave them running, so they
normally won't buzz when the alarm is "off". There's a circuit from
the cpu just to put the amps into sta
On Thu, Sep 13, 2007 at 06:52:49PM -0400, DJ Delorie wrote:
>
> Tougher to figure out, but at least I don't have to design a new power
> supply. Or explain why current on the +12 rail affects the 3.3v ldo
> on the other end of the board.
Have you made sure that both ends of all the components ar
Not to be insulting but is the speaker connected?
--
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> What kind of alarm does your alarm clock use?
It has an mp3 decoder in it, so you can pick anything from an annoying
beep to a streaming radio station across the planet.
http://www.delorie.com/electronics/alarmclock/
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What kind of alarm does your alarm clock use?
--
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> Hey you have two data points that alarm clocks must by their nature
> buzz!
None of the other alarm clocks in the house buzz, though.
Except when their alarms go off ;-)
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spaghetti -> keyboard
BWHAHAH!!
On Sep 13, 2007, at 7:26 PM, Steve Meier wrote:
> Hey you have two data points that alarm clocks must by their nature
> buzz!
>
> Steve M.
>
> On Thu, 2007-09-13 at 18:56 -0400, DJ Delorie wrote:
>>>Hey DJ...Look at it this way. If you can really h
Hey you have two data points that alarm clocks must by their nature
buzz!
Steve M.
On Thu, 2007-09-13 at 18:56 -0400, DJ Delorie wrote:
> >Hey DJ...Look at it this way. If you can really hear a faint
> > buzzing sound coming from your alarm clock, there's clearly not
> > enough equipment run
Also, replacing the PNP with a P-MOSFET doesn't change anything.
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On Sep 13, 2007, at 6:56 PM, DJ Delorie wrote:
>>Hey DJ...Look at it this way. If you can really hear a faint
>> buzzing sound coming from your alarm clock, there's clearly not
>> enough equipment running in your house.
>
> My wife said the same thing. However, *this* board is going in my
> b
>Hey DJ...Look at it this way. If you can really hear a faint
> buzzing sound coming from your alarm clock, there's clearly not
> enough equipment running in your house.
My wife said the same thing. However, *this* board is going in my
bedroom, on a table near my pillow, while I'm asleep.
On Sep 13, 2007, at 6:52 PM, DJ Delorie wrote:
>>> So, it's NOT the inductors!
>>>
>>> Whew.
>>
>> no not whew.
>>
>> tougher.
>
> Tougher to figure out, but at least I don't have to design a new power
> supply.
Hey DJ...Look at it this way. If you can really hear a faint
buzzing sou
> > So, it's NOT the inductors!
> >
> > Whew.
>
> no not whew.
>
> tougher.
Tougher to figure out, but at least I don't have to design a new power
supply. Or explain why current on the +12 rail affects the 3.3v ldo
on the other end of the board.
At least now it makes more sense; if it
On Sep 13, 2007, at 3:36 PM, DJ Delorie wrote:
So, it's NOT the inductors!
Whew.
no not whew.
tougher.
Steve
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> take your 3.3 volt bench supply and bypass the 3.3v switcher.
No change!
I took out the switcher and wired an LDO into the test points, same
symptoms as before.
The LDO got hot, which is why I went with a switcher - it's got to
drop 12-17v down to 3.3v with enough current to drive the cpu,
et
The only thing on the bottom of the board is a couple of bypass caps
(most are on the top) and some of the ethernet bias circuitry.
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On 9/13/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > Is the board in the Panavise while it is buzzing?
>
> I've already thought of that. It makes the same sound if I take it
> out and hold it in my hands, which are neither magnetic nor stiff like
> the panavise.
Do you have a picture that show
> Is the board in the Panavise while it is buzzing?
I've already thought of that. It makes the same sound if I take it
out and hold it in my hands, which are neither magnetic nor stiff like
the panavise.
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On 9/13/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > Pressing on each inductor with a wooden dowel didn't change the buzzing?
>
> Nope. However, pressing at random places on the board does, but only
> because it changes the (I think) wave inteference patterns. I.e. it
> has no effect if your
> Pressing on each inductor with a wooden dowel didn't change the buzzing?
Nope. However, pressing at random places on the board does, but only
because it changes the (I think) wave inteference patterns. I.e. it
has no effect if your ear is close enough, but further away, the
volume of the sou
On 9/13/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
> > I am assuming it is in the bottom right hand corner of the picture
> > where it looks like the switcher and the SM inductors are that it
> > seems to be coming from.
>
> The bottom right (the one with the three SMT inductors) is the 3.3v
> swit
> Have you tried the contact microphone (pizeo buzzer) yet to narrow
> down the location ? Hook it up to your sound card if you don't have
> a great scope.
I got an electret mic working, but it didn't pick up anything off the
board. Hmmm... do I even *have* a peizo buzzer?
I've got a "magnetic
Have you tried the contact microphone (pizeo buzzer)
yet to narrow down the location ? Hook it up to your
sound card if you don't have a great scope.
I am assuming it is in the bottom right hand corner of
the picture where it looks like the switcher and the
SM inductors are that it seems to be
take your 3.3 volt bench supply and bypass the 3.3v switcher. i have
heard others suggest this i think in the thread.
if the noise continues you know it is another source.
Steve
On Sep 13, 2007, at 11:58 AM, John Coppens wrote:
> On Thu, 13 Sep 2007 11:38:57 -0400
> DJ Delorie <[EMAIL PROTECT
On Thu, 13 Sep 2007 11:38:57 -0400
DJ Delorie <[EMAIL PROTECTED]> wrote:
> > Did you cheap out on the inductor?
>
> Not that I'm aware of. I used these:
By far the most probable cause is the inductor. I've made quite a few
switchers, and several of them caused problems. I'm not so preoccupied
w
On 9/13/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> > Does the switching power supply have a transformer?
>
> No, it's a simple buck converter.
Take a wooden dowel and try pressing on each of the inductors to see
if the intensity changes.
(* jcl *)
--
http://www.luciani.org
__
> Does the switching power supply have a transformer?
No, it's a simple buck converter.
> Does the frequency change when you change load?
No, just intensity.
> Is the output noise within the power supply specification?
The switcher's output is pretty clean, about 7 mVpp at 150 kHz.
The OLED
> Ceramic caps on a switching power supply can have a pizeo eletric
> effect. Try poscaps or a tant.
The switcher caps are tantalum. There are also two electrolytic bulk
caps, one on each side of the switcher.
Probably the best view of these is here:
http://www.delorie.com/electronics/alarmc
> So do OLED displays buzz themselves ?
No, it's definitely coming from the board somewhere.
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On 9/13/07, DJ Delorie <[EMAIL PROTECTED]> wrote:
>
> Ok, help me out with this one.
>
> The PCB for my alarm clock buzzes.
>
> It's really hard to tell which part is doing it, just from listening.
>
> The sound may be a combination of a high pitch whine and a 100hz buzz
> (the oled is 100hz).
>
>
Ceramic caps on a switching power supply can have a pizeo eletric
effect. Try poscaps or a tant.
Hook up a microphone and take a fft of the sound a sound card can do
it if you don't have a scope or spectrim analyzer.
Did you cheap out on the inductor? Try potting them with something,
I'
At 00:34 -0400 13-09-2007, DJ Delorie wrote:
>2. What kind of components *can* make that kind of noise?
Ceramic capacitors, especially high-K ones (Y5V,Z5U), can exhibit
signs of piezo-elektrickery. The supply decoupling banks of a
prototype pulse laser driver of mine buzz like a trapped hornet
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